dateadd 函数雪花中的变量

Question

我有这样的查询：

With cte as(
    Select min(date1) as min_date,
           max(date1) as max_date,
           id,
           city,
           time_id
   From some_table
   Group by id, city, time_id
),

range as
(select dateadd('month', row_number()over(order by null), (select min_date from cte)) as date_expand
From table(generator (row_count => 12*36))))

Select * from range;

它给出了这个错误：单行子查询 returns 多于一行。

有没有办法在 dateadd 函数的第三个参数中传递一个变量？因为我的cte会return many min_date based on the group by clause。 TIA

Answer 1

是的，SELECT 中的 sub-select 只需要 return 一行，你的 CTE 中有很多行。

如果你这样做的话，你的查询对我来说更有意义：

With some_table as (
    SELECT * FROM VALUES
        (1, 'new york', 10, '2020-01-01'::date),
        (1, 'new york', 10, '2020-02-01'::date),
        (2, 'christchurch', 20, '2021-01-01'::date)
    v(id, city, time_id, date1)
), cte as (
    Select 
       min(date1) as min_date,
       max(date1) as max_date,
       id,
       city,
       time_id
   FROM some_table
   GROUP BY 3,4,5
), range as (
    SELECT 
        id, city, time_id,
        dateadd('month', row_number()over(partition by id, city, time_id ORDER BY null), min_date) as date_expand
    FROM table(generator(rowcount =>12*36))
    CROSS JOIN cte
)
Select * from range;

但是如果你的 CTE 变成这样：

With cte as (
    Select 
       min(date1) as min_date,
       max(date1) as max_date
   FROM some_table
), range as (
    SELECT 
        dateadd('month', row_number()over(ORDER BY null), (select min_date from cte)) as date_expand
    FROM table(generator(rowcount =>2*4))
)
Select * from range;

这可行，因为只有一个 min_date 值 returned。

或者您可以找到 min_date 中最小的一个，例如：

WITH cte as (
    Select 
       min(date1) as min_date,
       max(date1) as max_date,
       id,
       city,
       time_id
   FROM some_table
   GROUP BY 3,4,5
), range as (
    SELECT 
        dateadd('month', row_number()over(ORDER BY null), (select min(min_date) from cte)) as date_expand
    FROM table(generator(rowcount =>2*3))

)
Select * from range;

dateadd 函数雪花中的变量

Variable in dateadd function snowflake

sql

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